1. Field Of The Invention
The present invention relates to a resist layer and its resist pattern formation process, said resist layer being particularly applicable to dry processes.
2. Description Of The Prior Art
Resist processes have long been applied to integrated circuit microprocessing, but advanced microprocesses have become necessary with the advent of advanced integrated circuits.
Resist processes broadly comprise a resist layer formation process, latent image formation process and a developing process. Conventional resist processes include the use of a fluid in a wet process in each of the above processing steps. In a resist layer formation process, for example, the resist layer is spread on a substrate. In a developing process a latent image is immersed in developing fluid and the soluble portion of the resist is dissolved so as to obtain a resist pattern.
These types of wet processes have the following disadvantages when applied to the formation of microresist patterns. In a resist layer formation process employing wet processes, the resist material is highly purified and coating homogeneity is regulated by controlling the composition, concentration, viscosity, dispersion processes and the like. Also, the application and polymerization processes are controlled due to the need to form a uniformly thin layer, thereby increasing processing complexity and costs, and reducing efficiency. Additionally, in related developing processes, decreased resolution induced by resist layer imbibition may result from the required use of a fluid developer, or an organic solvent, alkaline aqueous solution or like agent as a rinse. Furthermore, safety is reduced by the use of chemicals and pattern defects may arise due to dust adhesion during the drying process or transporting process.
Attention has recently been focused on dry processes which do not employ liquids for the resist formation process and/or developing process as a means of solving the aforesaid disadvantages.
Successful electron beam (EB) drawn resist layers applicable to resist processes in dry process resist formation and/or developing process are, for example, PMMA (KTI, DuPont, etc.), OEBR1030 (Tokyo Okasei), CP3 (Tokyo Okasei), EBR9 (Toray Industries), FBM (Daikin), PM (Microimage), PBS (Mead Tech), 1350 (Hoechst Shipley), RE5000P (Hitachi), and the like.
The aforesaid electron beam drawn resists, however, all lack adequately high sensitivity and are not sufficiently resistant to dry etching.
Conventional resist processes, on the other hand, require that the post-development negative resist layer remaining on the drawn portion of the resist and the post-development positive resist layer remaining on the non-drawn portion of the resist be properly handled according to the objectives. Accordingly, a problem arises wherein two types of resists, positive and negative, necessitate the selection of suitable resist materials.